Heat exchanger



July 26, 1955 J. E. PoTTHAsT, JR

4HET EXCHANGER INVENTOR. JOHN E.l POTTHARST, JR.

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FIG. 5.

2,713,996 Patented July 26, 1955 ice HEAT EXCHANGER John E. Pottharst,Jr., New rleans, La. Application @stoiber 23, 1952, Serial No. 316,481

` is Claims. (el. 257-247) This invention relates generally to heatexchangers and in particular to heat exchangers which may be readilyadapted and assembled to meet heating and cooling requirements over awide range and which further may be modified without difficulty as suchrequirements are changed from time to time.

The heat exchanger of my invention is composed of parts which may bestandardized and made interchangeable, facilitating assembly andreplacement of parts.

Also the component parts of my heat exchanger may be combined to meetthe heat exchange requirements of an installation without the necessityfor a specially built unit of iixed capacities for each installation. 1tis of considerable advantage in meeting the requirements for varioustypes of processing equipment having heat exchange problems, to avoidthe necessity if possible, of

Vmaking each heat exchanger custom built and permanent, particularly ifthe heat exchange requirements subsequently may be modified or varyingrequirements must be met by a manufacturer. The heat exchanger disclosedherein makes it possible to meet with exactitude, a Wide range ofheating or cooling requirements inasmuch as it is only necessary to addor subtract units providing a given amount of heating or coolingsurface. And in addition each unit may be easily assembled ordisassembled as will be subsequently disclosed.

A common problem in prior heat exchangers has been the diiiiculty ofinspection and the disassembling of the various tubular and connectingmembers for repairs and cleaning. These problems are even more seriousin systems involving the use of corrosive liquids, such as sea water andchemicals. Corrosion problems are ampliied where there is contactbetween metal surfaces or restricted areas in the flow paths Within thesystem. For that reason heat exchangers which permit the normallyconcentric tubes to come into substantial contact as a result of bowing,or which restrains bowing by the use of tins or supporting membersplaced in contact with a corrosive liquid, are particularly subject tothis hazard.

One of the objects of the present invention is to provide a novel typeof heat exchanger in which the parts are interchangeable and which maybe built up or compounded substantially as units to meet the heatexchange requirements of a given installation.

Another object of the present invention is to provide a heat exchangerwhich permits easy assembly and dis-V assembly and replacement of tubeparts as well as easy cleaning. A further object is to provide a heatexchanger in which corrosion and the problems of corrosion may be keptat a minimum.

For a better understanding of my invention reference may be had to thefollowing detailed descriptions taken in conjunction with theaccompanying illustrative drawings:

Figure 1 is a view in longitudinal section of one assembled end ofconnected pairs of concentric tubes;

Figure 2 is an intermediate section of a pair of concentric tubes andexternal supporting plate;

Figure 3 is a view in longitudinal section of the assembly connectingone of the tube ends of an assembled pair of concentric tubes (Figure l)with one of another assembled pair of concentric tubes;

Figure 4 is an alternative form of assembly similar to Figure 3;

Figure 5 illustrates a bank of heat exchange units showing the assemblyend, as in Figure 3; and

Figure 6 is a side elevation on a larger scale taken along lines 6-6 ofFigure 5, looking in the direction of the arrows.

In general, with regard to the heat exchange assembly illustrated forexample in Figure l, it Will be understood that the two inner tubes 10,suitable for carrying the inner fluid, are iixedly seated by soldering,brazing or other suitable means within the return bend 11, forming ineffect a forked assembly. This assembly in conjunction with the twoouter concentric tubes 12 carrying the outer iiuid is held in fluidtight relationship by the assembly illustrated in Figure 3, whichconnects each forked assembly (Figure l) with another.

With this general arrangement in mind, we refer now more specifically toFigure l in which it will be noted the inner tubes 10 fit snugly withinthe respective openings 13 and 14 of the return bend 11, which openingshave shoulders 15 against which the tubes 1) may bear. These tubes areiixedly retained within the openings 13 and 14 by soldering, brazing orother suitable means. Soft solder or silver solder may be used forexample, depending upon the type of liquid passing through the tubes.The inner tubes 10 may be of soft bronze and may be tinned if desired.Preferably there is no rolling or expanding of the tubes within thereturn bends. This permits replacement of the tubes 1t) or bends 11without destruction of the parts. It is one of the advantages of Vmyconstruction that the unit may be made of special metals or compositionsto meet precise processing conditions and may be assembled anddisassembled Without cause for injury to any such special materials.

The open ended tubes 10 of the forked assembly of Figure l, comprisingthe two tubes 10 and return bend 11, are positioned in an outer tubereturn bend 16 by passing them through the openings 17 thereof into theouter concentric tubes 12.

The outer tubes 12 are held in spaced relationship by a series of spacedsupporting plates 18; the outermost may be disposed adjacent to (andbetween) the outer tube return bends 16 to prevent the endwise movementof the tubes after the various parts are assembled. This arrangement isparticularly suitable when constructing portable units, however, it isto be understood that the supporting plates 18 may be disposeddifferently if so desired. in addition, the plates 18 are spaced atsuitable intervals to prevent the sagging or bowing of the outer tubes12, as can be seen in Figs. l, 2 and 3. A more detailed description ofthe plates 18 will be given in connection with Fig. 5.

The collar or return bend 16 for the outer tubes 12 has in it, twoshouldered openings 19 and 20 for receiving and seating firmly two outertubes 12. The ends of the outer tube 12 are preferably square cut andbear against a suitable gasket 21, of synthetic rubber for example. Itis of importance to note that the outer tubes 12 are not expanded,welded or otherwise deformed in any way when lthey are mounted in thesupporting plates or iitted into the return bends.

A fluid tight connection between the several parts of the assembly ofFigure l is provided for by the shoulders 22 on the return bend 11acting to seat the circular gaskets 23. These gaskets in turn provideseats for the inner beveled edges of the openings 17 of the return bend16. These gaskets preferably have the cross section of a right angletriangle. The right angle portions lits against the shoulder so as topresent a slanting face to the beveled edge of the openings i7 of thereturn bend i6. As will be subsequently described, when tension isimposed upon the forked assembly comprising tubes 1) and their returnbend il, the assembly of Figure l becomes fluid tight as the returnbends lo and lll are drawn tightly against the gaskets 23 and the outertubes 12 are drawn into and firmly seated in the return bend 16 andagainst the gasket 21.

Figure 2 shows an intermediate tube supporting plate 18 for thesurrounding outer tubes l2 and the inner tubes 10.

Figure 3 discloses an assembly for drawing together and holding iluidtight relationship several of the forked assemblies of Figure l. Theinner tubes itl of Figure 3, for example, represent one tube each of twodifferent forked units of the type illustrated in Figure l. The ends ofthe tubes lill of Figure 3 are fitted with threaded collars or sleeves24, which collars are tixedly attached by soldering, brazing or othersuitable means, but preferably without expanding for deformation of thetube itself. Each of these sleeves 2d carries an internally threadedcollar or tube nut 25 which bears preferably against one or more washers26 carried on the inner tubes, which washers in turn areV forced by athreading on of the tube nuts 25, against gaskets 27. These gaskets areof the same construction as the gaskets 23 of Figure l and return bendor collar lo and related assembly for the outer tube construction, isalso similar to that illustrated in Figure l. The tube nuts 25, whichare turned by a fork wrench against the washers 26, provide suitableprotection for the gaskets 27 during the tightening operation.

As the tube nuts 25 are screwed on to the threaded sleeves 24e, tensionis imposed upon the inner tubes ll@ and act to bring the assemblies ofFigures l and 3 into liquid tight relationship and also serves toprevent the inner tubes from bowing when subjected to heat. In

addition the act of tightening the tube nuts 25 insures aV furthercentering of the inner tube within the outer tube because of thepreviously described gasket and shoulder construction of the severalunits.

The open ends of the inner tubes 10 are closed by connesting` or returnbend 28, which have recess openings 29 to receive the tubes lil andsealing gaskets 3@ disposed therebetween.

The return bend 23 may be retained in position by bolts 3l passingthrough them and threaded into tapped openings 32 extending through theside of the tube nuts 25.

This arrangement permits the tube nuts 25 to serve as 1.

holding means without undue limitation on their rotational adjustmenteven when the tube assemblies are closely spaced. In addition thisarrangement acts to lock the tube nuts 25 in a fixed position preventingany loosening thereof as the result of vibration for example. The returnbend Z3 may be provided with a test plug or drain cock 33 which permitsthe fluid contained therein to be tested.

Figure 4 discloses an alternative form of assembly to that disclosed inFigure 3. ln this ligure, the inner tubes l0 are positioned within theconcentric outer tubes l2 in a manner similar to that described inconnection with Figures l, 2 and 3. The return bend or collar le of theouter tube .l2 and the related gasket construction 2l and 27 is alsosimilar to the construction described in con- J nection with Figure 3,except that it will be noted that the gasket 27 is illustrated assubstantially circular in cross section. 0f Course, a gasket oftriangular cross section may be used instead.

The inner tubes l@ extend through the suitable openings in the collarlo, and have attached to their surface by soldering or brazing, athreaded collar or sleeve 24 about which are passed washers 34 which areforced against the gasket 27 by the threadedcollar or tube nuts 25, whenthe latter is tightened. Any means may be used to attach the threadedcollar or sleeve 2d to the tube but it is preferably done withoutexpanding or distorting the tube within the sleeve.

The threaded sleeves 24- in the construction of Figure 4 are alsoutilized to carry internally threaded collars or pipe couplings 35disposed about the ends of the inner tube return bend Se. The threadedcouplings 35, in conjunction with shouldered collars 37, attached bysuitable means such as soldering or brazing to the ends of the returnbends 35, serve to draw the ends of the inner tubes i@ and shoulderedcollars against the gaskets 38 and into liquid tight relationship.

The inner tubes lt?, of the assembly of Figure 4, are brought undertension and the entire assembly maintained in fluid tight relationship(with the exception of the open ends of the tubes l0 subsequently to beclosed by the return bend 36) by the tightening of the tube nuts 25.rhis construction in that respect is similar to the assembly shown inFigures l to 3.

It can be appreciated that the various units can be readily disassembledby simply removing the inner tube return bends and unscrewing the tubenuts, which thereby permits the withdrawal of the fork assembly and theouter pipes and return bends associated therewith. If found defective,any of the various parts can be easily replaced for none are expanded ordeformed in any way in assembling. Another important advantage in thisarrangement is that if a leak develops in one of the inner or outertubes, the defective tube may be removed and temporarily repaired bysoldering or brazing and then reused in the system until a new part isobtained.

Figure 5 shows a bank of the units assembled for heat exchange purposes,the return bends 2S, the removable plug 33 and the retaining bolts 31being noted.

The tube support plate i8 has a suitable number of evenly spacedopenings 39 through which the outer tubes extend and are therebydisposed in a parallel and equidistant relationship. Extra openings mayalso be provided for supporting additional heat exchange assemblies ofthe type illustrated in Figures l to 4, inclusive.

The supporting plate is preferably made of a fiber-reinforced plasticcapable of having suicient strength when placed at intervals to supportthe tubes, but which will not scratch an assembly made of bronze orother soft materials. Furthermore, a plate of this construction has beenfound to be very satisfactory to minimize the elect of corrosion in theevent there is leakage. The tube plate, however, can be made of othermaterials, even metal, or combination of metal and plastic7 if sodesired.

The plates 18 are placed at suitable intervals along the length of theouter tubes (as illustrated in Figures l, 2 and 3) and as shown inFigure 5, are secured by bolts 40 to a metal frame 41, which frame maybe carried by suitable supports 42.

Referring to Figure 5 wherein is disclosed a multiple tube assemblywhich may be used in connection with the distillation of salt water, tocool the saline-free distillate and the blow down (salt concentrate),and to preheat the incoming brine. It is to be understood, of course,that my invention is not to be limited to this use alone and may be usedin connection with many other industrial operations wherein a heatexchange is required.

It will be noted that the various iiuids are fed into and dischargedfrom the system through a conventional inner and outer tube connection50 of the type illustrated in Figure 6, in which the outer opening 51communicates with the inner tubes, and the inner opening 52 communicateswith the concentric portions between the inner and outer tubes. It is tobe understood, of course, that other types or designs of inner and outertube connections may be used if conditions so require it.

The heat exchanger illustrated in Fig. 5 comprises fourteen Verticalrows of tubes. Distillate is admitted to the inner tubes at the left (asviewed in Fig. 5) through the inner tube connection at 51a and thcdistillate llows succession from one inner tube to the next through theinner tubes of the tive vertical rows at the left, finally emerging fromthe discharge connection at 51C; also distillate is admitted to theinner tubes at the right through the inner tube connection at 51h andflows in succession from one inner tube to the next through the innertubes of the ve Vertical rows at the right, finally emerging from thedischarge connection at 51d. For additional cooling, the distillateowing through the left-hand bank of inner tubes, is diverted (at 53) andconducted through the engine oil cooler (not shown) from where it isreturned to the system (at 54) and makes several more passes beforebeing discharged therefrom.

The salt water (cool) is fed into the outer tubes (the concentric spacesbetween the inner and outer tubes) through the outer tube connections52a and SZb situated at the lower part of the tube assembly. The brineentering the connection 52a flows through the outer tubes of the sevenleftward vertical rows of tubes and is fmally discharged at 52e, and thebrine entering the connection 52b ows through the outer tubes of theseven rightward vertical rows of tubes and is nally discharged at 52a.It will be noted that the distillate and brine llow in oppositedirections-through the system (see arrows in Figure 5).

The heat contained by the blow down (salt water concentrate) afterleaving the evaporator (not shown) may also be utilized in this assemblyto preheat the incoming brine. The blow down is fed into the center bankof inner tubes (rows 6, 7, 8 and 9) through the upper Y connection 56communicating with two inner tubes, and it is then passed through thecenter rows of inner tubes in the opposite direction to the flow path ofthe incoming brine and finally discharged through the lower Y inner tubeconnection 57.

The importance of the fact that the iiow path of the inner tubes neednot necessarily coincide with the outer tubes is apparent from the abovedescription of one use of my invention. For if this were not possible,the distillate and blow down which liow through three independent banksof inner tubes could not all be cooled by the incoming brine flowingthrough all of the outer tubes.

It Will also be appreciated that should it become necessary to modifythe heat exchange conditions, this can easily be done by changing theflow paths of the various liquids and by adding or subtracting thenumber of assemblies of the type illustrated in Figures l to 4, carriedby the supporting plates 18.

Another advantage of my heat exchanger construction is that the assemblyis of such a design that there is no necessity for providing access tothe sides thereof in order to remove or replace the various parts. As aresult, it is possible to place the tube assemblies, as described inFigures 1 to 4, in a very close relationship, as is seen in Figure 5. Inthis connection, it will be noted in Figures 3 and 5, that no part ofthe inner tube return bends or the Various fastening means, such as thetube nuts 25 or the screws 31, project beyond the collar or inner returnbend 16.

It will be understood, of course, that the various structural parats ofthis apparatus are susceptible to modification. Therefore, the form ofthe invention described above should be considered as illustrative andnot as limiting the scope of the following claims.

I claim:

l. A heat exchanger comprising, a plurality of concentrically mountedinner and outer tubes, connecting means between the ends of pairs ofouter tubes, connecting means between the ends of pairs of inner tubes,threaded means adjustable to produce relative axial movement between theinner and outer tubes to secure the outer tubes and the outer tubeconnecting means associated therewith in fluid tight relationship and toexert tension on said inner tubes.

2. In a heat exchanger as described in claim l, a plurality ofperforated plates to support said outer tubes in a parallel andequidistant relationship.

3. A heat exchanger comprising, a plurality of inner tubes, a pluralityof outer tubes of shorter length concentrically disposed about each ofsaid inner tubes, uid conveying members slidably mounted on the ends ofpairs of inner tubes connecting in fluid liow relationship the ends ofpairs of outer tubes, threaded members on at least one end of each ofsaid inner tubes adjustable to produce relative axial movement betweenthe inner and outer tubes to secure the outer tubes and fluid conveyingmembers associated therewith in uid tight communication and to exerttension on said inner tubes and fluid conveying member connecting saidinner tubes.

4. In a heat exchanger as described in claim 3, in which at least one ofthe inner tube fluid conveying members connecting the ends of said pairsof inner tubes have locking means operative with said threaded membersto secure said inner tube fluid conveying members in fluid tightcommunication with said inner tubes.

5. In a heat exchanger as described in claim 3, a series of perforatedplates to support said outer tubes in a parallel and equidistantrelationship.

6. A heat exchanger comprising a plurality of tubes, connecting means tojoin the ends of pairs of said tubes, a plurality of inner tubesconcentrically mounted within said tubes and extending through openingsin the connecting means associated therewith, uid conveying means toconnect the ends of pairs of inner tubes, threaded means on the oppositeends of said inner tubes adjustable to produce relative axial movementbetween the inner and outer tubes to secure the outer tubes andconnecting means associated therewith in a tluid tight relationship andto exert tension on said inner tubes.

7. In a heat exchanger as described in claim 6, fluid conveying membersto connect said opposite ends of pairs of said inner tubes and fasteningmeans to secure said fluid conveying members in liquid communicationwith said inner tubes.

8. In a heat exchanger as described in claim 6, a plurality ofperforated plates to support a varying number of said tubes in aparallel and equidistant relationship, the outermost of said platesbeing adjacent to-and between said connecting means to prevent theendwise movement of said tubes.

9. In a heat exchanger a Huid conveying assembly comprising, a pluralityof tubes, uid connecting means to join the ends of pairs of said tubes,a plurality of U- u shaped fluid conveying members the arms of whichextend through openings in said fluid connecting means and areconcentrically disposed within said tubes, threaded means on the ends ofsaid U-shaped fluid conveying members adjustable to produce relativeaxial movement between the arms and the tubes to secure said tubes andfluid connecting means associated therewith in fluid tight relationshipand to exert tension on said arms of said U-shaped fluid conveyingmembers.

l0. A heat exchanger comprising a plurality of tubes,

f removable connecting means to join the ends of pairs of said tubes, aplurality of U-shaped fluid conveying members the arms of which extendthrough openings in said removable connecting means and areconcentrically disposed within said tubes, threaded means on the ends ofsaid U-shaped fluid conveying members adjustable to produce relativeaxial movement of said arms relative to the tubes to secure said tubesand removable connecting means associated therewith in uid tightrelationship and to exert tension on said arms of said U-shaped fluidconveying members, removable fluid conveying members to connect pairs ofends of said U- shaped fluid conveying members and fastening means tomaintain said removable fluid conveying members in liquid tightcommunication therewith.

11. In a heat exchanger as described in claim 9, a

plurality of parallel perforated plates to support a varying number ofsaid tubes in a parallel and equidista'nt relationship, the outermostplates being adjacent to and between said removable connecting meansassociated therewith to prevent the endwise movement of said tubes.

12. In a heat exchanger assembly, a plurality of tubes, removable Huidconnecting means to connect the ends of said tubes, a plurality of innertubes substantially concentrically disposed within said tubes with theends thereof extending through openings in said removable iluid outertubes to maintain said tubesV and the removable fr fluid connectingmeans associated therewith in uid tight relationship.

13. A heat exchanger comprising, a plurality of tubes, a plurality ofplates to support a varying number of said tubes in a parallel andequidistant relationship, removable connecting means to join the ends ofadjacent pairs of said tubes, a plurality of inner tubes concentricallymounted within said tubes and extending through openings in saidremovable connecting means associated therewith, fluid conveying meansto connect the ends of adjacent pairs of inner tubes, a threaded portionat the opposite ends of said inner tubes, fastening means on saidthreaded portions to secure said outer tubes and said removableconnecting means associated therewith in uid tight communication and toexert tension on said inner tubes, flanged fluid conveying members toconnect the opposite ends of different adjacent pairs of said innertubes, threaded means extending through openings in the anged portion ofthe said last-mentioned uid conveying members and into aligned openingsin said fastening means to secure the former in liquid tightcommunication with said opposite ends of said inner tubes,

ifgcrenees Cited in the le of this patent UNTED STATES PATENTS LIL@

